In wireless communications, with the rapid increase of the density of wireless users, the capacity of a wireless cellular system is required to be greater and greater. In order to effectively increase the capacity of a wireless cellular system, the most effective method is to reduce a cell radius, that is, to develop from a macro cell towards a micro cell. In order to adapt to the construction of base station by using this method, a base station is usually split into a remote radio unit (RRU) and a base band unit (BBU). The cost of such a distributed base station is only a part of the cost of a complete base station, although there are the largest number of the RRUs thereof. Thus, the design of a distributed base station can effectively reduce the cost of base station construction.
A complete base station may include a unit for processing upper layers of a wireless data link layer (optional), a wireless data link layer processing unit (optional), a BBU, an intermediate frequency (IF) processing unit, a radio frequency (RF) post-processing unit, and an antenna and RF pre-processing unit. After the base station is split into two parts of RRU and BBU, the functions of each part are as shown in FIG. 1. The RRU includes an antenna and RF pre-processing unit, an RF post-processing unit, and/or an IF processing unit. Correspondingly, the BBU at least includes a BBU and may further include an IF processing unit, a wireless data link layer processing unit (optional), and a unit for processing upper layers of a wireless data link layer (optional). If the RRU includes an IF processing unit, as shown in (a) in FIG. 1, interacting between the RRU and the BBU may be performed by using an IF digital signal in time division multiplexing (TDM) mode. For example, interacting between the RRU and the BBU is performed by using a Common Public Radio Interface (CPRI). If the BBU includes the IF processing unit, as shown in (b) in FIG. 1, interacting between the RRU and the BBU may be performed by using an RF digital signal in TDM mode.
A distributed base station can effectively reduce the network construction cost of the cellular system. However, the design has the following problem: Currently, RRU and BBU devices produced by different manufacturers cannot match each other and the privatization of interfaces is serious.